Now, being a rational guy, I know dreams don't mean anything.
They are just random barrages of neurons firing which sometimes
manage to activate parts of your occipital cortex, where all your
visual system wiring is. Your cerebral cortex has no choice but to
try to make sense of this madness, and so when you wake up, you've
got a more-or-less coherent story. Pure illusion. The mind is an
awesome thing.

Then again, this is not to say that there isn't some
significance to the images that get awakened. What that
significance is, no real scientist has been willing to risk their
career trying to figure out, but there are two theories that have
happened to stick in my head:

One, dreams are the side effect of sorting and transporting
memories from your hippocampus (short-term memory) to various parts
of your cerebral cortex (where long-term memory is stored in
various cubbyholes and niches), through the fornix and various
thalamic relays, either incidentally or deliberately lighting up
your visual cortex. So the images may or may not be related to your
most recent thoughts. It's all in the wiring.

Two (as expounded by Sir Francis Crick, co-discoverer of the
structure of DNA), dreams are an "unlearning" process. Ideas that
are deemed unusable or detrimental by the brain are extricated,
accidentally lighting up your visual cortex on their way out.

So, what it comes down to is this: are dreams about thoughts
that are supposed to be remembered, or about thoughts that are
supposed to be forgotten? To put it another way, are dreams about
things you want to come true, or about things that you don't want
to come true?

And if you believe in a fatalistic, deterministic universe
(which, in true quantum mechanical fashion, sometimes I do, and
sometimes I don't), then what it could mean is this: are dreams
things that are going to come true, or things that are definitely
not going to come true?

Let's just say that I had some pretty intense dreams last night.
Not XXX graphic or anything like that (get your mind out of the
gutter). But the emotions I experienced in them felt like they were
going to make my heart burst. And when I woke, I felt a bit sad and
forlorn, because it hit me that it was just a dream.